The field of computed radiography (CR) is well known. In the field of computed radiography, a photographic element has an image formed thereon by x-rays. The photographic element is subsequently provided to a reader wherein the element is stimulated to emit a radiation pattern that is indicative of the image formed by the x-rays. Typically, storage phosphors are used to capture radiographic images from incident x-rays. Most radiographic procedures are carried out within normal room lighting conditions, accordingly, a primary requirement for any computed radiography x-ray cassette is to shield the storage phosphor from exposure by ambient light.
One kind of cassette used in computed radiography can comprise a container having upper and lower parts that are hinged together so they can be opened for insertion of a flexible film sheet comprising the photographic element. The cassette is closed and latched so that the cassette with the photographic element therein can be used with an x-ray apparatus to produce an image on the photographic element. The cassette is then taken to a reader where the cassette is opened and the photographic element is extracted by suitable feeders, such as a suction feeding device. The photographic element separates from the cassette and is transported through the reader where it is stimulated to emit a radiation pattern that is captured for storage and use. The radiation pattern is subsequently erased from the photographic element before being returned to the cassette for re-use. U.S. Pat. No. 5,276,333 (Robertson), commonly assigned and incorporated herein by reference, disclosed such a cassette.
Another kind of cassette used in computed radiography is disclosed in U.S. Pat. No. 5,861,631 (Wendlandt), U.S. Pat. No. 5,869,839 (Wendlandt), U.S. Pat. No. 5,943,390 (Wendlandt), and U.S. Pat. No. 6,683,315 (Wendlandt), all commonly assigned and incorporated herein by reference. In this kind of cassette, generally shown in FIGS. 1 and 2, a rigid film plate supports the photographic element. As shown in FIGS. 1 and 2, cassette assembly 10 is comprised of a storage phosphor assembly 12 and a shell 14. Shell 14 includes an upper and lower panel and two side members forming a cavity 16. Storage phosphor assembly 12 includes rigid insert plate 18 adapted to be removably contained within cavity 16 of shell 14. Insert plate 18 supports storage phosphor screen 20, which includes a layer of storage phosphor. Insert plate 18 can be comprised of one or more layers, for example as shown in FIG. 2, two rigid layers (for example, aluminum) 22,24, and a honeycomb layer 26.
While such cassettes have achieved certain degrees of success in their particular applications, it may be desirable to provide a cassette having a rigid insert plate supporting a single storage phosphor screen wherein each of the two sides (i.e., front and back surfaces) of the storage phosphor screen is substantially optically and/or radiographically visible. By substantially optically visible, it is meant that both sides of the screen are detectable using an optical means/device disposed on one or both sides of the screen. By substantially radiographically visible it is meant that both sides are detectable using a radiographic means/device. More particularly, that a radiation pattern disposed on the screen can be obtained from both sides using a radiographic means/device. It is recognized that a level of visibility is variable, and can be dependent on the amount of light and/or x-ray energy used/received.
In addition, it may be desirable to provide a cassette having a rigid insert plate supporting a storage phosphor screen on both sides of the insert plate wherein at least one side/surface of each storage phosphor screen is optically and/or radiographically visible.
The present invention provides a storage phosphor cassette having a single storage phosphor screen mounted on a rigid support wherein each side of the storage phosphor screen is optically and/or radiographically visible. The present invention further provides a storage phosphor cassette having two storage phosphor screens mounted on at least one rigid support wherein at least one side/surface of each storage phosphor screen is optically and/or radiographically visible.